• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2001년도 춘계학술발표대회 개요집
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• pp.224-227
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• 2001

In this study, CT specimens were prepared hem ASTM SA516 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -l$0^{\circ}C$ and -l2$0^{\circ}C$ and in the range of stress ratio of 0.1, 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range $\Delta K_{th}$ in the early stage of fatigue crack growth ( Region I ) and stress intensity factor range $\Delta$K in the stable of fatigue crack growth ( Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN - $\Delta$K in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate da/dN is rapid in proportion to descend temperature in Region H and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• 한국축산식품학회지
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• 제26권3호
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• pp.356-361
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• 2006

This study was carried out to investigate the physico-chemical and storage characteristics of sausages added mugwort powder at $4^{\circ}C$ during 13 days. The composition of fresh sausages was as the following : meat 60 % (w/w), lard 20 %, ice 20 %, salt 1.5 %, sugar 0.5 %, phosphate 0.25 %, mugwort 2 % or 5 %. Sausages were divided into three groups; control group mugwort 0 %, Treatment I mugwort 2 % and Treatment II mugwort 5 %. The pH, TBA(thiobarbituric aid) value, VBN(volatile basic nitrogen), rheology, and sensory evaluation were measured. The changes of pH of all groups were slightly decreased with increasing storage days. But, the significant difference of pH changes were not shown between mugwort 2 % (Treatment I) and mugwort 5 % (Treatment II) groups. The changes of TBA values of all treatments increased during storage periods. TBA values of Treatment I and Treatment II groups were significantly (p<0.05) higher than that of the control group. The change of VBN showed trends to increase during storage periods. The change of VBN of Treatment I was significantly (p<0.05) lower than those of the control and Treatment II. Hardness and brittleness of 2 % and mugwort 5 % groups were significantly (p<0.05) higher than that of the control group. Elasticity and cohesiveness of 2 % and Treatment II were significantly (p<0.05) lower than that of the control group. Also, Treatment I was superior to the other groups by the results of sensory evaluation. Therefore, these results suggest that it may be possible to manufacture sausages added 2 % mugwort powder which can help to increase storage periods, and improve quality of sausage.

• 한국식품영양과학회지
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• 제36권2호
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• pp.241-245
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• 2007

영양학적, 생리학적 장점이 많은 표고버섯을 다양한 식품으로 이용하기 위한 적절한 가공방법을 모색하여 고부가가치를 갖는 식품으로 개발을 하고자 표고버섯을 첨가한 강정을 제조하여 첨가 수준별 품질특성을 조사하였다. 표고버섯 첨가 강정의 일반성분은 첨가량이 증가하면서 수분, 조단백질과 회분 함량은 증가하였고, 탄수화물 함량은 감소하였으며, 조지방은 차이를 보이지 않았다. 색도를 분석한 결과 L값은 대조구가 59.10로 가장 높았으며, 표고버섯 첨가량이 증가할수록 유의적으로 감소하였다. b값은 L값과 같은 경향을 보였으며, a값의 경우 증가하였다. 또한 모든 첨가구에서 대조구와 현저한 색의 차이를 보이는 것으로 나타났다. 강정의 물성 측정 결과 gumminess, brittleness, cohesiveness, springiness는 대조구와 20%, 30% 시료에서는 큰 차이를 보이지 않았으며, 40% 첨가구부터 그 값이 유의적으로 증가하였고, hardness의 경우 40% 첨가구까지 큰 차이를 보이지 않았다. 시료별 관능검사 결과는 색(color), 향미(flavor), 맛(taste), 바삭바삭한 정도(crispiness)와 전반적인 기호도(overall acceptability) 등 모든 검사 항목에서 30% 첨가구가 가장 높은 점수를 받았으며 40% 이상 첨가시 기호도가 조금씩 감소하는 것으로 나타났다. 쌀강정에 표고버섯을 일정 비율로 첨가하여 표고버섯 강정을 제조하고, 여러 특성을 조사한 결과 기존의 쌀강정에 비하여 표고버섯 첨가 강정이 더 우수한 제품이 될 수 있었고, 최적의 첨가량은 쌀 튀밥을 기준으로 30%로 나타났다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 춘계학술대회 논문집
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• pp.320-325
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• 2001

In this study, CT specimen were prepared from Pressure Vessel Steel which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -10$0^{\circ}C$ and -12$0^{\circ}C$ and in the range of stress ratio of 0.05 and 0.3 by means of opening mode displacement. At the constant street ratio, the threshold stress intensity factor range ΔK$_{th}$ in the early stage of fatigue crack growth(Region I) and stress intensity factor range ΔK in the stable of fatigue crack growth(Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm do/dN -ΔK in RegionII, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It was assumed that the fatigue crack growth rate do/dN is rapid in proportion to descending temperature in Region IIand the cryogenic-brittleness greatly affect a material with decreasing temperature.e.greatly affect a material with decreasing temperature.

• Advances in concrete construction
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• 제4권2호
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• pp.71-88
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• 2016

Metakaolin, a dehydroxylated product of the mineral kaolinite, is one of the most valuable admixtures for high-performance concrete applications, including constructing reinforced concrete bridges and impact- and fire-resistant structures. Concretes produced using metakaolin become more homogeneous and denser compared to normal-strength concrete. Yet, these changes cause a change of volume throughout hardening, and increase the brittleness of hardened concrete significantly. In order to examine how the use of metakaolin affects the fracture and mechanical behavior of high-performance concrete we produced concretes using a range of water to binder ratio (0.42, 0.35 and 0.28) at three different weight fractions of metakaolin replacement (8%, 16% and 24%). The results showed that the rigidity of concretes increased with using 8% and 16% metakaolin, while it decreased in all series with 24% of metakaolin replacement. Similar effect has also been observed for other mechanical properties. While the peak loads in load-displacement curves of concretes decreased significantly with increasing water to binder ratio, this effect have been found to be diminished by using metakaolin. Pore structure analysis through mercury intrusion porosimetry test showed that the addition of metakaolin decreased the critical pore size of paste phases of concrete, and increasing the amount of metakaolin reduced the total porosity for the specimens with low water to binder ratios in particular. To determine the optimal values of water to binder ratio and metakaolin content in producing high-strength and high-performance concrete we applied a multi-objective optimization, where several responses were simultaneously assessed to find the best solution for each parameter.

• 한국식품저장유통학회지
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• 제16권1호
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• pp.53-59
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• 2009

The purpose of this research is to develop bellflower (Platycodon grandiflorum) root and lotus (Nelumbo nucifera) root Jeonggwa as a health food. The quality characteristics of Jeonggwa to which 0-8% (w/w) of Omija (Schizandra chinensis Baillon) water extract was added were investigated. The moisture contents of bellflower root Jeonggwa were 14.9-18.0%, where as that of lotus root Jeonggwa was 6.9-8.4%. The acidity of bellflower root Jeonggwa was 0.477-0.585% and that of lotus root Jeonggwa was 0.513-0.572%; values increasing levels of Omija extract. The lightness (L) and yellowness (b) values of bellflower root Jeonggwa decreased with increasing amounts of Omija extract, and the lightness (L), redness (a) and yellowness (b) values of lotus root Jeonggwa decreased with increasing Omija extract concentration (p<0.05). In mechanical tests with bellflower root Jeonggwa, the highest values of hardness and strength were seen at 2% (w/w) extract, of cohesiveness were seen with 4-8%, of springiness with 2-6%, of gumminess with 6-8%, and of brittleness with 4-6% (all p<0.01). In mechanical tests with lotus root Jeonggwa, the highest values of hardness and springiness were at 0 and 6% extract, respectively, whereas strength, gumminess and brittleness were at 6-8% Omija extract (all p<0.01). In sensory evaluation, the highest acceptability of bellflower root Jeonggwa was seen with 4% extract and that of lotus root Jeonggwa was seen with 2% extract.

• 한국식품저장유통학회지
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• 제22권1호
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• pp.78-83
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• 2015

강황 분말을 0, 2, 3, 4%를 첨가한 어묵을 제조하여 색도, 절곡검사, 조직감, 관능검사 등의 품질 특성을 조사하였다. 색도 변화는 L, a값은 강황 분말의 첨가량이 증가할수록 감소하였고 b값은 증가하였다. 어묵의 유연성과 탄력성을 나타내는 절곡검사에서는 대조군을 포함한 모든 시료에서 AA로 측정되어 강황 분말의 첨가에 관계없이 우수한 것으로 나타났다. 강황 분말을 첨가한 어묵의 기계적 texture 특성은 강황 분말 첨가량이 증가할수록 경도(hardness), 응집성(cohesiveness), 탄력성(springiness)은 증가하였고, 검성(gimminess)과 파쇄성(brittleness)은 감소하였다. 관능검사 결과로 색깔(color), 향미(flavor), 조직감(texture), 맛(taste), 전체적인 선호도(overall acceptance)는 3%의 첨가군이 가장 높은 평가를 받았다. 따라서 강황 분말을 첨가한 기능성 강황 어묵의 가공 적성에 적절한 강황의 첨가량은 3%가 적당하다고 사료되며 강황을 함유한 고품질 어묵의 제조 가능성을 확인하였다.

• 한국재료학회지
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• 제21권11호
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• pp.592-595
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• 2011

It is well known that modified 9Cr-1Mo steel has a low thermal expansion and high thermal conductivity with excellent high temperature properties compared to austenitic stainless steel. For these advantages, the steel is very popular for the boiler tube of thermal power plants. Normalizing is commonly utilized to obtain martensite in this steel, which shows an unusual toughness for martensite. However, some accidents related to this steel have been reported recently, opening the necessity for further study. As a particular behavior of the steel, an abrupt drop of the impact value has been identified upon tempering at 750$^{\circ}C$ for about 1 hour. It is well known that $Fe_3C$ forms during autotempering and turns to $Cr_2C$ at an early stage and then transforms to $Cr_{23}C_6$. In this study, the cause of the abrupt drop of the impact value was investigated with an impact test, microstructural observation, nanodiffraction and phase analyses using instruments such as optical and transmission electron microscopes (TEM) with an extraction carbon replica of the carbides. The analyses revealed that the $M_2C$ that formed when retained for about 1 hour at 750$^{\circ}C$ causes a drastic decrease in the mechanical properties. The sharp drop in mechanical properties, however, disappeared as the $M_2C$ transformed into $M_{23}C_6$ with longer retention.

• 한국식품영양학회지
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• 제30권4호
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• pp.681-688
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• 2017

This study was conducted to investigate the effect of gelatin concentration and storage on color and texture of puffer fish stock jelly. Puffer fish stock jelly was prepared by adding various amounts (2.5~10 percent) of gelatin to puffer fish stock. Color changes of puffer fish sstock jelly were also investigated during storage at $4^{\circ}C$ and $25^{\circ}C$ with varying amount of gelatin (2.5~10.0 percent). Regardless of storage temperature, the L values of puffer fish stock jelly were slightly increased, while a values of the stock jelly were negatively decreased during storage. However, L and negative b values were decreased with increasing gelatin concentration, whereas a values were increased negatively with increasing gelatin concentration. The texture profiles of puffer fish stock jelly such as hardness, springiness, cohesiveness adhesiveness, chewiness and brittleness were determined during storage at $25^{\circ}C$ and $4^{\circ}C$ at various intervals. The hardness, chewiness and brittleness were increased during storage at $25^{\circ}C$ for four days, while those of springiness and cohesiveness were decreased during storage. However, the values of all textural parameters were increased with increasing gelatin concentration in puffer fish stock jelly. Patterns of textural parameters of puffer fish stock jelly stored at $4^{\circ}C$ were practically identical to those stored at $25^{\circ}C$.

• 한국가스학회지
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• 제2권3호
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• pp.1-11
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• 1998

열 수축 쉬-트용 점착제의 접착성, 내한성 및 유동성을 향상시키기 위해 점착제를 구성하는 각 성분들의 종류 및 함량에 따른 물성을 평가하였다. 본 연구에서는 베이스 폴리머로서 내후성이 우수한 부틸고무를 선정하여 실험을 진행하였다. 점착부여제는 석유계 수지가 로진보다 우수한 접착력을 나타내었으며, 함량이 감소함에 따라 유동성이 저하됨을 알 수 있었다. 폴리부텐은 저 분자량보다 고 분자량의 물성이 우수하였다. 카본블랙의 경우 입자경이 클수록 물성 향상에 유리하였다. 탄산칼슘을 중량제로서 혼입할 경우 카본블랙과 함께 혼합시키는 경우가 바람직하였다.